the fact that a line contains a test is somewhere in the
middle, so not too obvious

normal sub calls, like now

ok $x eq 'foo', 'description';
dies_ok { ... }, 'description';

pros:

easier to implement

it's been proven to work out well

visually tests are very easy to spot

cons:

it's *very* hard to get good diagnostics out of failed tests
(advanced macro fiddling needed)

clutters up namespace

if we don't deprecate is(), we have to find sane comparison
semantics, fix up the tests (we have to do that anyway...)
and educate our test writes. Currently infix:<eqv> is a
candidate (advocated by pmichaud, because it's very dwimmy),
infix:<eq> being another (advocated by mority, because it's
very simple and easy to explain).

Backends and standard backend

all the test logic should be easily overridable (for example for storing